Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/24003—Shapes of record carriers other than disc shape
  • G11B7/24009—Tapes, long films or long sheets
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
  • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
  • G11B7/244—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only
  • G11B7/245—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only containing a polymeric component
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
  • G11B7/26—Apparatus or processes specially adapted for the manufacture of record carriers
  • G11B7/263—Preparing and using a stamper, e.g. pressing or injection molding substrates
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24479—Structurally defined web or sheet [e.g., overall dimension, etc.] including variation in thickness

Definitions

• the present invention relates to optical tape storage technology and in particular to methods for making optical tape.
• the typical optical tape medium includes a base film such as polyethylene naphthalate (PEN) over-coated with multiple layers for recording digital data.
• a polymeric imprint layer is usually disposed over the base film.
• the imprint layer is over-coated with a reflective metallic layer that is, in turn, over- coated with a sequence of dielectric layer, phase change layer, and dielectric layer.
• the actual data recording and reading occurs in the phase change layer.
• a pulsed laser beam is projected from an optical head assembly onto the optical tape thereby causing a phase change in the phase change layer that results in data being encoded therein.
• Data encoded onto the optical tape is also read with a laser with the reflective layer reflecting light to a detector.
• optical tape usually includes optical servo marks embossed into the imprint layer along the length of the tape for operating with a servo control system for controlling the optical head, Although l the current optical tape technology works reasonably well, there are a number of problems related to the polymeric imprint layer.
• the imprint layers tend to cause a number of detrimental effects due to dimensional changes that occur therein. For example, such dimensional changes may cause thickness variations in the metal and dielectric layers. Although these effects are believed to be due to poor mechanical and thermal properties of the imprint polymer, it is also thought that the sensitivity of the imprint layer to electron beam damage during the metal layer and dielectric layer depositions also contributes to these changes.
• the present invention solves one or more problems of the prior art by providing, in at least one embodiment, a method for forming an optical tape for data storage from a substrate film.
• the method of the present embodiment includes a step of patterning a curable liquid composition onto the substrate film.
• the curable liquid composition comprises a free radical photoinitiator and a polymerizable component that includes at least one acrylate.
• the curable liquid composition coated on the substrate film is illuminated with actinic radiation to form a patterned imprint layer disposed over the substrate film.
• a multilayer data recording assembly is placed over the second imprint layer side to form the optical tape.
• the imprint layer formed in the present embodiment is less susceptible to electron beam damage and has improved mechanical stability as compared to the imprint layers currently used to fabricate optical tape medium.
• a method for forming an optical tape for data storage from a substrate film is provided.
• the substrate film includes a first substrate side and a second substrate side.
• the method of the present embodiment includes a step of patterning a curable liquid composition onto the substrate film.
• the curable liquid composition comprises a free radical photoinitiator and a polymerizable component that includes at least one acrylate.
• the curable liquid composition coated on the substrate film is illuminated with actinic radiation (e.g., UV radiation) to form a patterned imprint layer disposed over the substrate film.
• actinic radiation e.g., UV radiation
• a metal layer is deposited over the patterned imprint layer.
• a first dielectric layer is then deposited onto the metal layer.
• a phase change layer is then coated onto the first dielectric layer.
• a second dielectric layer is deposited onto the phase change layer.
• an imprint layer formed by the methods set forth above includes the residues of a free radical photoinitiator and of a polymerizable component (e.g., monomer) that includes at least one acrylate.
• the imprint layer optionally further comprises the residues of a free radical photoinitiator.
• Figure 1 is a top view of an optical tape medium incorporating an embodiment of an imprint layer
• Figure 2 is a cross sectional view of an optical tape medium incorporating an embodiment of an imprint layer
• Figure 3 is a schema illustration of a system for forming an optical tape medium.
• percent, "parts of,” and ratio values are by weight; the description of a group or class of materials as suitable or preferred for a given purpose in connection with the invention implies that mixtures of any two or more of the members of the group or class are equally suitable or preferred; description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among the constituents of a mixture once mixed; the first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation; and, unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.
• FIG. 1 is a top view of the optical tape medium.
• Figure 2 is a cross sectional view of the optical tape medium.
• Optical tape 10 includes substrate film 12 having substrate film sides 14, 16.
• substrate film 12 is formed from polyethylene naphthalate (PEN).
• Imprint layer 20 is disposed over substrate film side 16.
• Imprint layer 20 includes imprint layer side 22 and imprint layer side 24 with imprint layer side 22 being more proximate to substrate film 12.
• imprint layer 20 is made by the process set forth below.
• Multilayer data recording assembly 28 is disposed over imprint layer 20.
• Multilayer data recording assembly 28 typically includes one or more layers involved in the optical recording of data.
• Multilayer data recording assembly 28 includes metal layer 30 disposed over imprint layer side 24.
• Metal layer 30 includes metal layer side 32 and metal layer side 34.
• Metal layer side 32 is more proximate to imprint layer 20 than metal layer side 34.
• Multilayer data recording assembly 28 also includes dielectric layer 40 disposed over metal layer side 34.
• Dielectric layer 40 includes dielectric layer side 42 and dielectric layer side 44 which is more proximate to metal layer 30.
• Multilayer data recording assembly 28 further includes phase change layer 50 which is disposed over dielectric layer 40.
• Phase change layer 50 includes phase change layer side 52 and phase change layer side 54 which is more proximate to phase change layer 50.
• the present embodiment also includes multilayer data recording assembly 28.
• Multilayer data recording assembly 28 also includes dielectric layer 60 disposed over metal layer side 54.
• Optical tape-forming system 70 includes spool 72 which supplies substrate film 16 which is of a tape-like configuration. During operation of optical tape-forming system 70, substrate film 12 moves in the directions indicated by d ds and is guided by direction rollers 74-82. Substrate film side 16 of substrate film 12 is coated with a curable liquid composition 86 from dispenser 88.
• curable liquid composition 86 includes free radical photoinitiator and a polymerizable component that includes at least one acrylate.
• dispenser 88 is used to coat curable liquid composition 86 onto substrate film 12.
• Coated substrate film 94 includes curable liquid layer 96 disposed on substrate film 12. Coated substrate film 94 proceeds to patterning roller 98. Patterning roller 98 includes protrusions 100 that define the pattern to be imprinted upon coated substrate film 94. Curing energy source 102 directs actinic radiation onto curable liquid layer 96 to induce radical polymerization therein to form imprint layer 20. Typically, curing energy source 102 is an ultraviolet ("UV") light source. Heat source 104 is optionally present in order to provide heat to assist in the curing. After curing, imprint layer 20 has pattern 106 imprinted therein [0021] Still referring to Figure 3, multilayer data recording assembly 28 is fabricated along direction d 5 .
• UV ultraviolet
• metal deposition station 1 10 is used to deposit metal layer 30 over imprint layer 20.
• deposition processes that may be used include sputtering and evaporation.
• metal deposition 1 10 is a sputtering reactor.
• Substrate film 12 proceeds next to dielectric deposition station 1 12 to form dielectric layer 40.
• Phase change layer 50 is coated onto dielectric layer 40 at phase change coating system 1 14.
• phase change layer 50 is a metal alloy, which has significant optical and electrical differences between the amorphous and crystalline states.
• Dielectric layer 60 is deposited onto phase change layer 50 via dielectric deposition station 1 16. It should be appreciated that metal layer 30, dielectric layers 40, 60 and phase change layer 50 can be single or multilayer structures.
• optical tape 10 is rolled onto spool 120.
• the optical tape formed by the present method is observed to have superior mechanical and thermal properties.
• the method allows for the imprint layer to be formed with a thickness less than about 2 microns.
• the imprint layer has a thickness less than about 1 .5 microns.
• the imprint layer has a thickness greater than from about 0.1 to about 0.5 microns.
• the imprint layer has a thickness greater than about 0.2 microns.
• the imprint layer has a thickness between 0.3 and 0.4 microns.
• the imprint layer has a thickness from about 0.1 to about 0.25 microns.
• the optical tape processing is paused after formation of the imprint layer.
• the coated substrate may be rolled onto a spool for later processing.
• the optical tape may be subjected to a slitting process in order to fit in a cartridge.
• the curable liquid composition has a viscosity less than about 50 cps at 25° C.
• the curable liquid composition has a viscosity less than about 30 cps at 25° C.
• the curable liquid composition has a viscosity less than about 20 cps at 25° C.
• the curable liquid composition has a viscosity less than about 10 cps at 25° C.
• the curable liquid composition has a viscosity greater than about 2 cps at 25° C.
• the curable liquid composition has a viscosity greater than about 5 cps at 25° C.
• the curable liquid composition includes one or more acrylates. Examples of suitable acrylates include monoacrylates, diacrylates, higher order functionality acrylates, and combinations thereof.
• the polymerizable component(s) are present in an amount from about 90 to about 99 weight percent of the total weight of the curable liquid composition. In another refinement, the polymerizable component(s) are present in an amount from about 93 to about 99 weight percent of the total weight of the curable liquid composition. In still another refinement, the polymerizable component(s) are present in an amount from about 95 to about 99 weight percent of the total weight of the curable liquid composition.
• the curable liquid composition includes an acrylate having formula I:
• Ri is hydrogen or substituted or unsubstituted alkyl; and R2 is a substituted or unsubstituted alkyl having more than 3 carbon atoms, cycloalkyl, cycloalkenyl, or substituted or unsubstituted aryl.
• Ri is hydrogen or methyl; and R 2 is n-butyl, t-butyl, isobornyl, phenyl, benzyl, dicylcopentenyl, dicyclopentenyl oxyethyl, ethylene glycol dicyclopentyl ether, cyclohexyl, and naphthyl.
• the most preferred ethyleneically unsaturated monomers are isobornyl acrylate monomers.
• a particularly useful monomer is provided by the following formula:
• the curable liquid composition also includes compounds having formula II:
• R 3 is hydrogen or substituted or unsubstituted alkyl (e.g., methyl, ethyl, etc) and R 4 is a hydrocarbon moiety.
• R is an alkylene group.
• R is describe by -(CH 2 ) n - where n is an integer from 1 to 10.
• the compound having formula II has the following formula:
• the curable liquid composition includes a combination of the compound having formula 1 and the acrylate having formula II.
• the acrylate having formula I is present in an amount from about 55 weight percent to about 75 weight percent of the total weight of the curable liquid composition and the acrylate having formula II is present in an amount from about 25 weight percent to about 45 weight percent of the total weight of the curable liquid composition.
• the curable liquid composition further includes a free radical photoinitiator.
• Suitable free radical photoinitiators include, but are not limited to, benzophenones, acetophenone derivatives, and combinations thereof. Specific examples include, alpha- hydroxyalkylphenylketones, benzoins (e.g., benzoin alkyl ethers and benzyl ketals), monoacylphosphine oxides, bisacylphosphine oxides, and combinations thereof.
• a particularly useful photoinitiator is Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide.
• the free radical photoinitiatior is present in an amount from about 0.1 to about 10 weight percent of the total weight of the curable liquid composition. In another refinement, the free radical photoinitiatior is present in an amount from about 0.5 to about 8 weight percent of the total weight of the curable liquid composition. In still another refinement, the free radical photoinitiatior is present in an amount from about 1 to about 5 weight percent of the total weight of the curable liquid composition.
• the various methods of the present invention are used to form a polymeric imprint layer as set forth above. Therefore, the imprint layer is characterized by including residues of one or more of the acrylates set forth above. In particular, the imprint layer includes residues of the compounds describe by Formula I and II. The imprint layer also includes residues of the free radical photoinitiator(s)set forth above.
• a polymeric imprint layer is made by coating a mixture having about 66 weight percent Isobornyl acrylate, 30 weight percent 1 ,6-Hexanediol diacrylate, and 4 weight percent Bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide onto a substrate film. The coated substrate film to then cured with UV light while passing over a patterning roller to form the imprint layer.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Manufacturing Optical Record Carriers (AREA)
• Polymerisation Methods In General (AREA)
• Optical Record Carriers And Manufacture Thereof (AREA)

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• 2010
  • 2010-06-24 US US12/822,592 patent/US20110318534A1/en not_active Abandoned
• 2011
  • 2011-06-24 EP EP11731590.3A patent/EP2586027B1/en active Active
  • 2011-06-24 CA CA2803281A patent/CA2803281C/en active Active
  • 2011-06-24 JP JP2013516787A patent/JP5879341B2/ja active Active
  • 2011-06-24 WO PCT/US2011/041737 patent/WO2011163543A1/en not_active Ceased

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